[PATCH 5.15.y 1/2] can: use skb hash instead of private variable in headroom

commit d4fb6514ff8ed6912a71294e6b66a5d59ee88007 upstream.

The can_skb_priv::skbcnt variable is used to identify CAN skbs in the RX
path analogue to the skb->hash.

As the skb hash is not filled in CAN skbs move the private skbcnt value to
skb->hash and set skb->sw_hash accordingly. The skb->hash is a value used
for RPS to identify skbs. Use it as intended.

Signed-off-by: Marc Kleine-Budde <[email protected]>
Signed-off-by: Oliver Hartkopp <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Oliver Hartkopp <[email protected]>
---
 drivers/net/can/dev/skb.c |  2 --
 drivers/net/can/slcan.c   |  1 -
 include/linux/can/core.h  |  1 +
 include/linux/can/skb.h   |  3 ---
 net/can/af_can.c          | 14 +++++++++++---
 net/can/bcm.c             |  2 --
 net/can/isotp.c           |  3 ---
 net/can/j1939/socket.c    |  1 -
 net/can/j1939/transport.c |  2 --
 net/can/raw.c             |  7 +++----
 10 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index e59d5cbb644a..ec624cfc1b07 100644
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c
@@ -201,11 +201,10 @@ struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
 	skb_reset_network_header(skb);
 	skb_reset_transport_header(skb);
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	*cf = skb_put_zero(skb, sizeof(struct can_frame));
 
 	return skb;
 }
@@ -232,11 +231,10 @@ struct sk_buff *alloc_canfd_skb(struct net_device *dev,
 	skb_reset_network_header(skb);
 	skb_reset_transport_header(skb);
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
 
 	return skb;
 }
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index d42ec7d1bc14..2ace2b735c20 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -211,11 +211,10 @@ static void slc_bump(struct slcan *sl)
 	skb->pkt_type = PACKET_BROADCAST;
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = sl->dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	skb_put_data(skb, &cf, sizeof(struct can_frame));
 
 	sl->dev->stats.rx_packets++;
 	sl->dev->stats.rx_bytes += cf.len;
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 5fb8d0e3f9c1..3287232e3cad 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -56,8 +56,9 @@ extern void can_rx_unregister(struct net *net, struct net_device *dev,
 			      canid_t can_id, canid_t mask,
 			      void (*func)(struct sk_buff *, void *),
 			      void *data);
 
 extern int can_send(struct sk_buff *skb, int loop);
+void can_set_skb_uid(struct sk_buff *skb);
 void can_sock_destruct(struct sock *sk);
 
 #endif /* !_CAN_CORE_H */
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index d311bc369a39..f887eb21e178 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -41,17 +41,15 @@ struct sk_buff *alloc_can_err_skb(struct net_device *dev,
  */
 
 /**
  * struct can_skb_priv - private additional data inside CAN sk_buffs
  * @ifindex:	ifindex of the first interface the CAN frame appeared on
- * @skbcnt:	atomic counter to have an unique id together with skb pointer
  * @frame_len:	length of CAN frame in data link layer
  * @cf:		align to the following CAN frame at skb->data
  */
 struct can_skb_priv {
 	int ifindex;
-	int skbcnt;
 	unsigned int frame_len;
 	struct can_frame cf[];
 };
 
 static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
@@ -105,11 +103,10 @@ static inline bool can_skb_headroom_valid(struct net_device *dev,
 
 	/* af_packet does not apply CAN skb specific settings */
 	if (skb->ip_summed == CHECKSUM_NONE) {
 		/* init headroom */
 		can_skb_prv(skb)->ifindex = dev->ifindex;
-		can_skb_prv(skb)->skbcnt = 0;
 
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 		/* perform proper loopback on capable devices */
 		if (dev->flags & IFF_ECHO)
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 85b01dea76df..95b7cc548675 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -639,10 +639,20 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf
 	}
 
 	return matches;
 }
 
+void can_set_skb_uid(struct sk_buff *skb)
+{
+	/* create non-zero unique skb identifier together with *skb */
+	while (!(skb->hash))
+		skb->hash = atomic_inc_return(&skbcounter);
+
+	skb->sw_hash = 1;
+}
+EXPORT_SYMBOL(can_set_skb_uid);
+
 static void can_receive(struct sk_buff *skb, struct net_device *dev)
 {
 	struct can_dev_rcv_lists *dev_rcv_lists;
 	struct net *net = dev_net(dev);
 	struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
@@ -650,13 +660,11 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
 
 	/* update statistics */
 	atomic_long_inc(&pkg_stats->rx_frames);
 	atomic_long_inc(&pkg_stats->rx_frames_delta);
 
-	/* create non-zero unique skb identifier together with *skb */
-	while (!(can_skb_prv(skb)->skbcnt))
-		can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
+	can_set_skb_uid(skb);
 
 	rcu_read_lock();
 
 	/* deliver the packet to sockets listening on all devices */
 	matches = can_rcv_filter(net->can.rx_alldev_list, skb);
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 2cf63940f6a9..235156223394 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -336,11 +336,10 @@ static void bcm_can_tx(struct bcm_op *op, struct canfd_frame *cf)
 	if (!skb)
 		goto out;
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	skb_put_data(skb, cf, op->cfsiz);
 
 	/* send with loopback */
 	skb->dev = dev;
@@ -1575,11 +1574,10 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk,
 		kfree_skb(skb);
 		return -ENODEV;
 	}
 
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 	skb->dev = dev;
 	can_skb_set_owner(skb, sk);
 	err = can_send(skb, 1); /* send with loopback */
 	dev_put(dev);
 
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 34939744dd41..b6b301f54e31 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -216,11 +216,10 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus)
 		return 1;
 	}
 
 	can_skb_reserve(nskb);
 	can_skb_prv(nskb)->ifindex = dev->ifindex;
-	can_skb_prv(nskb)->skbcnt = 0;
 
 	nskb->dev = dev;
 	can_skb_set_owner(nskb, sk);
 	ncf = (struct canfd_frame *)nskb->data;
 	skb_put_zero(nskb, so->ll.mtu);
@@ -771,11 +770,10 @@ static void isotp_send_cframe(struct isotp_sock *so)
 		return;
 	}
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	cf = (struct canfd_frame *)skb->data;
 	skb_put_zero(skb, so->ll.mtu);
 
 	/* create consecutive frame */
@@ -1067,11 +1065,10 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 		goto err_out_drop;
 	}
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	so->tx.len = size;
 	so->tx.idx = 0;
 
 	cf = (struct canfd_frame *)skb->data;
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index ec2927566cf3..540836c4964d 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -887,11 +887,10 @@ static struct sk_buff *j1939_sk_alloc_skb(struct net_device *ndev,
 	if (!skb)
 		goto failure;
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = ndev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 	skb_reserve(skb, offsetof(struct can_frame, data));
 
 	ret = memcpy_from_msg(skb_put(skb, size), msg, size);
 	if (ret < 0)
 		goto free_skb;
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 55bbcf73c873..74638cf04172 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -610,11 +610,10 @@ sk_buff *j1939_tp_tx_dat_new(struct j1939_priv *priv,
 		return ERR_PTR(-ENOMEM);
 
 	skb->dev = priv->ndev;
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = priv->ndev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 	/* reserve CAN header */
 	skb_reserve(skb, offsetof(struct can_frame, data));
 
 	/* skb->cb must be large enough to hold a j1939_sk_buff_cb structure */
 	BUILD_BUG_ON(sizeof(skb->cb) < sizeof(*re_skcb));
@@ -1549,11 +1548,10 @@ j1939_session *j1939_session_fresh_new(struct j1939_priv *priv,
 		return NULL;
 
 	skb->dev = priv->ndev;
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = priv->ndev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 	skcb = j1939_skb_to_cb(skb);
 	memcpy(skcb, rel_skcb, sizeof(*skcb));
 
 	session = j1939_session_new(priv, skb, size);
 	if (!session) {
diff --git a/net/can/raw.c b/net/can/raw.c
index b489689ada33..ffbb622f8842 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -72,12 +72,12 @@ MODULE_ALIAS("can-proto-1");
  * list containing only one item.  This common case is optimized by
  * storing the single filter in dfilter, to avoid using dynamic memory.
  */
 
 struct uniqframe {
-	int skbcnt;
 	const struct sk_buff *skb;
+	u32 hash;
 	unsigned int join_rx_count;
 };
 
 struct raw_sock {
 	struct sock sk;
@@ -134,22 +134,22 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (!ro->fd_frames && oskb->len != CAN_MTU)
 		return;
 
 	/* eliminate multiple filter matches for the same skb */
 	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
-	    this_cpu_ptr(ro->uniq)->skbcnt == can_skb_prv(oskb)->skbcnt) {
+	    this_cpu_ptr(ro->uniq)->hash == oskb->hash) {
 		if (ro->join_filters) {
 			this_cpu_inc(ro->uniq->join_rx_count);
 			/* drop frame until all enabled filters matched */
 			if (this_cpu_ptr(ro->uniq)->join_rx_count < ro->count)
 				return;
 		} else {
 			return;
 		}
 	} else {
 		this_cpu_ptr(ro->uniq)->skb = oskb;
-		this_cpu_ptr(ro->uniq)->skbcnt = can_skb_prv(oskb)->skbcnt;
+		this_cpu_ptr(ro->uniq)->hash = oskb->hash;
 		this_cpu_ptr(ro->uniq)->join_rx_count = 1;
 		/* drop first frame to check all enabled filters? */
 		if (ro->join_filters && ro->count > 1)
 			return;
 	}
@@ -827,11 +827,10 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	if (!skb)
 		goto put_dev;
 
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
 
 	err = memcpy_from_msg(skb_put(skb, size), msg, size);
 	if (err < 0)
 		goto free_skb;
 
-- 
2.53.0